Flotation of uranium



Patented Aug. 4, 1953 lS'IATS iQltiTE-NT OFfFI CE `FLUTATION F URANIUM "sion @No Drawing. .Application August 25, 1950,

Serial No. 181,563

1 Claim. 11

y This-invention relates to I.the :recovery of mineral values from -ores and `the like and, .more fparticularly, to the recovery `of luranium values lby :an :improved notation procedure.

yUranium lvalues'can be recovered by a notation fprocedure wherein the sole flotation agent used .is chosen from the class consisting of anionic .and ...non-.ionic synthetic detergents and `soluble salts of .fatty Aacids and `rosin acids. However, .While uranium values can be recovered from gangue materials :by -that process, only part of .the .uranium 'values present can be so separated Within .a'practical ,length of time, and the recoveryof `thefsaiol values from the froth by means .of which they @are separated from gangue is tedious, diiilcult 'and :expensive .inasmuch as large .quantitieszof'organic solvents are required in the breaking of the froth when those l.synthetic detergents especially suited to the recovery of uranium materials l'are used .as frothing agents, or special high-pressure sprays or quantities of acid are .required in order 'to break "the'io'am of less reflective soaps.

Itis an object of this invention to provide an lvimproved :flotation procedure .for the recovery of uranium values from ores and the like.

It 'is 'another :object vof this vinvention lto rpro-- vicle an improved A'flotation procedure 'for there- .covery of .uranium values'irom ores and the like wherein theiroth bymeans :of'Which the uranium values are separated is readily broken.

'Itis Astill a further object of 'this vinvention to provide a lmethod l"for 'the recovery .of uranium values :from yores and like :materials wherein substantially all of the uranium 'values `may .be 'recoveredby means 0i `a simp'le and expeditious process.

lIt is 'a 'still further object 'of this .invention to vprovide am'ethod 'for recovering 'uranium values 'from artificial ore-like materials rsuch vas `earth materials icontaining uranium oxides and the like -Whic'h have been inadvertently `spilled thereon, earth materials containing uranium values :scattered 'therein 'during testing procedures, or uranium values recovered from fluid systems by a sand-lterer the like.

Other objects and advantages will become apparent from the description and examples which follow.

Theiprocess of this invention isfcarried out by using,fin fa-.conventional flotation procedure, an agent v`consisting of a material y.chosen Y'from the .class nf anionic and non-,ionic synthetic detergents together with a material chosen from the class of soluble salts 'of "fatty acids 'and resin acids. .By means of `such a :combination of :flotation agents, kit ihas rbeen "-.foun'd that substantially 90 per cent for Lm'ore `of the uranium values .in :an

(Cl. 20g- 166) .ore may .conveniently be vrecovered and that .the foam, by means of which `these 4uranium values are separated from `.the Agangue materials, .may readily be ,broken by .conventional techniques, Vsuch as the 4useof water sprays ordilute acids.

.In carrying out the process .oi this invention, conventional flotation procedures may be .used .providing `the .notation Iagent of .this invention vemployed 4Without the Ausual addition agents. '-iiT-hile the Iaddition -of such Vother rmaterials .as conditioners, promoters, vfvrothers or depressants .may be employed, they have .not been .found .to .contribute materially to .the results obtained by the useef the .single combination flotation .agent of the syntheticzdetergent together with the soap.

While the supplementaryagents ingeneral have not been found to interfere severely with .the process ci the invention, neither .have they lbeen found to `ina-ke .any contribution .to the process.

Steps in the Vconventional flotation procedure nusually :comprise .Wet Agrinding .and classifying the material to be treated; adding, to this intimate mixture of Water and finely divided ore materials, one or more notation agents; permitting adequate contact to be established between 'the agent andthe particles; agitating 'the pulp; forming froth thereon, usually Lby passing air through `a body oi pulp; separating the froth; `breaking 'the froth to recover the mineral 'values therefrom. Any convenient apparatus suitable for such Aflotation procedure 'may be used in carrying `out the ,process Ioi this invention.

In Athe examples vwhich 'follovv, two -diierent types of 4apparatus Varei'zlescribed': (l) A vsingle `cell "batch otationunit used 'for testing purposes and, (2) an eightell `continuous flotation Iunit inwhich recovery of -themineral values from the 'ore is leiiected on ya continuous basis, Aeach cell serving to 4refine the tailings from the Vpreceding `cell 'until substantially lcomplete removal 4of the uranium values from the ore has "been effected.

In `any flotation procedure, it is Well-'established that the specification of roptimum concentration of the ctationagent cannot be made without detailed consideration of the particular forematcrial and Lniineral'valuesrto be separated.

'in gen'eral,.fin 'carrying out ithe :process :of :this invention, .satisfactory results tare #obtained by using Ithe yconcentration .of -lagent .which fis :dieterzi-lined to vbe lslightly .aabove 'the :minimum 'conycentration l.necessary `for Imainta-.innig Atroitlfiing :on thepulp in Aquestioni. The usual amountisof :the fonder ci f0.1 poundto l0 .pounds :of lincitation `agent per'tonof oren'leiterial. However, tfhefbe ihavior Vof particular Iore materials `varies.- jIn "order to .secure best t'results, it tmay be necessary Jto =`establish the exact 'ratio iof :synthetic detergent to soap which gives the most satisfactory recovery and the most easily broken foam, and to establish the amount of combined frothing flotation agent which is most effective. As indicated above, in general, this concentration lies just above that minimum concentration necessary to affect frothing. The use of smaller or larger amounts of flotation agent often leads to less satisfactory results; the use of more flotation agent, in addition, is wasteful and uneconomical. It should be further pointed out that the use of a thick pulp is often conducive to obtaining` a satisfactory result with smaller amounts of otation agent.

As is well-known in the mineral dressing art, advantage may be taken of the differing response to grinding procedures, of the different constituents of ore materials. Many ore materials contain some components which are softer or more easily broken down than others. If the softer components are desired materials, they may be conveniently recovered at an appropriate size, from the coarser gangue, or, as undesired materials, they may be ground so finely as to be left behind more readily, especially in a flotation procedure.

Other process variables in the flotation procedure may also affect the success thereof. The use of elevated temperatures, the use of soft water, and the allowing of adequate contact between the flotation agent and the pulp to be treated are all well-known in the art. A general and explicit description of surface active agents may be found in Surface Active Agents by Schwartz and Perry, published in 1949 by Interscience Publishers, Inc., New York. In particular, the class of non-ionic detergents and the type herein characterized as polyethylene oxidetype or polyethylene oxide-phenol type is described and delimited on pages 202 ff. of this referenced publication.

Eazample I To a single cell batch flotation unit comprising a otation box, an air supply on the bottom thereof, an agitator and a foam-removing paddle, there is charged 3.5 liters of water containing 0.1 gram of ethylene oxide polymer condensed with a phenol nucleus and 0.22 gram of sodium salt of mixed fatty acid, the fatty acids comprising mainly stearic acid, together with 1000 grams of gangue material which is shown by analysis to contain grams of uranium oxide (USOS). Flotation procedure is initiated. In five minutes, 67 per cent of the uranium value has been recovered in the froth and, after thirty minutes, better than 99 per cent of the uraniurnvalue has been recovered in the froth. The froth, by means of which the mineral values are recovered, is readily broken by the use of dilute acids or by the use of a high-pressure spray of water alone.

Example I I To the apparatus of Example I containing a charge of 1000 grams of gangue material which is shown by analysis to contain 20 grams of uranium dioxide (U02), there is added 3.5 liters of solution containing 14 milligrams of polyethylene oxide-phenol detergent and 170 milligrams of sodium oleate per liter. Flotation is carried out. In the froth that is floated during the first ve minutes, there is recovered 95 per cent of the uranium value and, at the end of thirty minutes, better than 99 per cent of the uranium values have been recovered in the easilybroken froth.

i Example III The apparatus of the preceding example is operated with a charge of 1 kilogram of gangue material containing 25 grams of mixed uranium oxides and a solution containing per liter 25 milligrams of sodium dodecylbenzenesulfonate and 150 milligrams of commercial red oil neutralized with caustic soda. Flotation procedure gives a recovery of about 95 per cent of the uranium values in thirty minutes.

Example IV An eight-cell continuous flotation unit wherein each cell has a capacity of 1 cubic foot is employed in the continuous operation to separate uranium oxide from gangue materials. The flotation agent, polyethylene oxide-phenol detergent, l part, with rened tallow soap, 2.2 parts, is maintained at a concentration just slightly above that necessary to maintain a froth on the system. No modifiers, promoters or depressants are used. Uranium oxide-sand material (1:3200) is fed at the rate of 200 pounds per hour to the operating system, water is re-circulated at the rate of about 4 gallons a minute around the entire system, and air is blown through each cell at an approximate rate of l cubic foot per minute. Somewhat better than 90 per cent of the uranium values are recovered with an average gangue flotation of about 1.2 per cent. Expressed in a different fashion, better than 90 per cent of the uranium values charged to the system are recovered together with about V85 of the original undesired material with which the uranium Values were mixed.

Example V In a similar run with the same material where the uranium values were present to the extent of 1 part of uranium oxide to 2000 parts of gangue material, 85 per cent of the total uranium charge is recovered. The gangue flotation is approximately seven-tenths of 1 per cent, representing almost a one hundred forty fold reduction in gangue material.

The foregoing examples are given by way of illustration only and are not to be considered as limiting in any way upon the scope of the invention. The invention is not to be limited except as indicated in the appended claim.

What is claimed is:

The process of recovering uranium values from ores and like materials which comprises pulping the finely divided material with water, adding a polyethylene oxide-,phenol detergent and a sodium salt of at least one fatty acid, and subjecting said pulp to flotation procedure whereby uranium values are concentrated in the froth and may be recovered therefrom.

PRESTON L. VELTMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,337,548 Edser Apr. 20, 1920 2,000,656 Armstrong May 7, 1935 2,012,609 Lenher Aug. 27, 1935 2,498,656 De Groote Feb. 28, 1950 OTHER REFERENCES Schwartz et al., Surface Active Agents, DD. 202 and 203 (1949). Published by Interscience Publication, Inc., New York, New York. 

